Download Chapter 1 Definitions

Chapter 1 Definitions
*Collinear Points
A set of points which lie on the same straight line.
Noncollinear
points
*Parallel lines
A set of 3 or more points that do not all line on the same straight line.
*Skew lines
2 non-coplanar lines that do not intersect.
*Coplanar Points
Points that lie in the same plane.
Betweenness
B is between A and C if and only if A, B, and C are distince dolliear
points and AB + BC = AC.
line segment
A set of points consisting of 2 points on a line called endpoints, and all
of the points between the endpoints.
2 coplanar lines that do not intersect.
length(measure) of The distance between endpoints.
a line segment
Congruent
segments
Segments with the same measure.
Midpoint of a line
segment
A point on the line segment that divides the segment into 2 congruent
segments.
Bisector of a line
segment
A line, segment, plane, or ray that intersects a segment at its midpoint.
Sum of two line
segments
xy + yz = xz if y is between x and z.
Half-line
A set of points on one side of a point.
Ray
A point on a line and all points on one side of the point.
Opposite rays
Two rays that lie on the same line with a common endpoint, but no
other points in common. They form a straight line/angle.
Angle
A figure formed by 2 non-collinear rays that have the same endpoint.
Straight angle
A figure formed by 2 opposite rays.
Acute angle
An angle whose measure is greater than 0° and less than 90°.
Right angle
An angle whose measure is exactly 90°.
Obtuse angle
An angle whose measure is greater than 90° and less than 180°.
Congruent angles
Angles that have the same measure.
Angle bisector
A ray that divides an angle into two congruent adjacent angles.
Perpendicular
lines
Two lines that intersect to form right angles.
Distance from a
point to a line
The lengths of the perpendicular from the point to a line.
Sum of two angles
The sum of  RSQ and  QST is  RST if Q is in the interior of  RST.
Polygon
A closed figure in a plane made up of line segments that intersect only
at their endpoints, and no segments that share an endpoint are
collinear.
Triangle
A polygon with exactly 3 sides.
Scalene triangle
A triangle with no congruent sides.
Isosceles triangle
A triangle that has 2 congruent sides.
Equilateral triangle A triangle that has 3 congruent sides.
Acute triangle
A triangle that has 3 acute angles.
Right triangle
A triangle that has 1 right angle.
Obtuse triangle
A triangle that has 1 obtuse angle.
Equiangular
triangle
A triangle that has 3 congruent angles.